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[How do I?] R 8 Adapter

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Billh51

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#1
I have a few questions on a r 8 adapter for my mill. I own a Hougen Mag drill and have a fairly large assortment of bits to go with it and would like to use them on the mill. I have been looking in various places and have found that an R 8 to a 3/4" Weldon shank adapter is fairly expensive. Depending what brand and where you buy it will run from about $60.00 to about $135.00. Some of them you can still use the center pin and others you can't but with a DRO, that shouldn't make to much difference.

My other thought is an R 8 to 3/4" end mill holder. Most of these that I have looked ar only have one set screw for the bit shank but my mag drill only uses one set screw also. I don't know the standard depth on a end mill holder because at this point I don't have any. I thought of you were able to set the Weldon shank up to its shoulder you may be able to drill and tap a new set screw to accommodate the flat on the shank. Also the price on a end mill holder is a heck of a lot cheaper.

Maybe some of you have run into this situation and can suggest what may be the best way to go.
Thanks, Bill
 

Silverbullet

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#2
If you have a lathe, why not make an adapter with the set screws to straight 3/4" . Then just use a regular r8 3/4" collet. Pretty straight forward machining. Of course you can watch for a used one also. A 2" x 6" piece of 4140 or A2 shouldn't cost to much.
 

Wreck™Wreck

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#3
Grind a flat for the tool holder set screw in the appropriate position by hand, done deal. I realize this method will make some hobbyists uncomfortable because of the appearance, how it looks means nothing if the tool works.
I often hand grind flats on drill shanks when holding them in lathe tool holders and mill holders.

There is no reason not to do so.
 

Billh51

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#4
Thanks for the reply. I do have a lathe also, so machining something is not a problem. I guess mainly my question is what's the difference between the two holders. Is the Weldon shank adapter made with a closer tolerance? They both do about the same thing as far as I can tell. Unless someone has a response not to, I think I will buy the R8-3/4" end mill holder and do any machining that needs to be done and save a lot of money.
 

Rustrp

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#5
I use my 3/4" R8 collet for my annular cutters and I have Jancey, Black &Decker, Hougen and Unibor. They all work. Before by next project my plan is to fab an ejector for the slug. A little math and a pin/spring arrangement between the end of the draw bar and the top of the center pin for the cutter should clear the slug with no problems. I really haven't had any problems with the slugs dropping out and the few that don't just need a little nudge with an awl or scribe. The only thing I watch for is to make sure I have the narrow surface of the shank (between the two set screw flats) not resting on one of the collet slits. I've never had one slip but using them on the Bridgeport was the first time I crashed one. Brand new 9/16", second hole and $$ green colored butterflies fluttered away.

Edit: Based on the comments, your cutters have a 3/4" shank. Hougen has the standard shank in their 12,000 series and a couple of other quick change styles where tools are not required. I'm not sure how their R8 adaptor is different than a collet, with the exception of the "Oil Inducer" which I could pass on. I prefer to lubricate as needed versus wear the oil that isn't needed.
 
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Billh51

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#7
Ok, thanks for the tips guys. I think my questions have been answered. I have a nice selection of annular cutters, mostly Hougen Rota Broach. Seems like such a waste that they sit in a drawer most of the time because I don't use the mag drill that often. This way I can make good use of them.
 

Rustrp

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#8
Ok, thanks for the tips guys. I think my questions have been answered. I have a nice selection of annular cutters, mostly Hougen Rota Broach. Seems like such a waste that they sit in a drawer most of the time because I don't use the mag drill that often. This way I can make good use of them.
You already know they make holes fast and I use mine for light milling in aluminum. Slotting obround holes etc. I don't think I would do this in steel but they seem to do well in aluminum. I also like the $$ for resharpening which is about 25% of new cost.
 
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